CN112399903A

CN112399903A - Method for thermally connecting two workpiece sections

Info

Publication number: CN112399903A
Application number: CN201980046721.7A
Authority: CN
Inventors: 米夏埃尔·布吕根布罗克
Original assignee: ThyssenKrupp Steel Europe AG; ThyssenKrupp AG
Current assignee: ThyssenKrupp Steel Europe AG; ThyssenKrupp AG
Priority date: 2018-07-12
Filing date: 2019-07-11
Publication date: 2021-02-23
Anticipated expiration: 2039-07-11
Also published as: WO2020011912A1; CN112399903B; US20210323099A1; DE102018211574A1; DE102018211574B4

Abstract

The invention relates to a method for thermally connecting at least two workpiece sections, wherein at least a first and a second workpiece section are provided, wherein at least the first workpiece section comprises an edge (1.1, 1.1') and the edge (1.1, 1.1') defines a terminal end of the edge section (1.2, 1.2'), the first and the second workpiece section being positioned relative to each other in such a way that they are connected to each other at least sectionally within their longitudinal extension, wherein the edge section (1.2, 1.2') has a defined geometry. According to the invention, the defined geometry of the edge section (1.2, 1.2') is dimensioned such that in a cross-section of the edge section (1.2') a maximum thickness (t) is provided at a distance (1.3') from the edge (1.1') in a cross-section of the edge section (1.2')_max1') Or is provided with at least one maximum thickness (t) starting from the edge (1.1, 1.1 ", 1.1" ') in the transverse extension of the edge section (1.2, 1.2 ", 1.2"')_{max1，max1”，max1”'}) Segment (1.3, 1.3 ", 1.3"').

Description

Method for thermally connecting two workpiece sections

Technical Field

The invention relates to a method for thermally connecting at least two workpiece sections, wherein at least a first and a second workpiece section are provided, wherein at least the first workpiece section comprises an edge and the edge defines a terminal end of the edge section, the first and the second workpiece section being positioned relative to each other such that they are connected to each other at least in sections in their longitudinal extent, wherein the edge section has a defined geometry.

The invention also relates to a workpiece set.

Background

The body is assembled from a number of components, in particular these components are connected to one another according to the usual convention, in particular are thermally connected to one another, preferably welded to one another. The joints or welds on or between the components in the vehicle body typically define weak points in the vehicle body structure. Under stress of (indeterminate magnitude), for example in the form of an accident, the weld seam created between at least two components after the heat welding process is not the cause of failure, but rather a transition region from the base material of one or more components to the weld seam, which in the case of heat welding is defined as the heat affected zone (WEZ). The material properties in the WEZ change due to melting and subsequent solidification of the base material.

The production of multiphase, ultra-high-strength high-quality steels for modern automotive bodies is characterized by its special chemical composition, and by a thermomechanical rolling process with a small process window. By thermal joining of these steels, this microstructure of ferrite, bainite and/or martensite of the steel obtained is cost-adjusted to melt in the center of the joint and to cool in an undefined manner. In the region of the heat-affected zone, the microstructure is subjected to an undefined heat treatment due to the heat conduction from the melted region. The change in material or material properties in the joint area (connection/weld and WEZ) is called metallurgical notch.

Another failure location or crack initiation location in the joint area is referred to as a geometric notch. The notch effect is caused by geometric inhomogeneities of the weld seam. Especially at the transition from the base material to the weld metal, there is a sharp edge which is at least directly in the force flow of the joint and may be the starting point of a crack and thus may lead to joint failure. For component walls above 2 … 4mm (depending on the weld shape), DIN EN ISO 9692-1: 2013, whereby a single-layer or multi-layer weld with root and top layer is formed over the entire material cross section of the base material. The weld preparation corresponds to the removal of material by grinding, milling, sawing or cutting, so that the welding source enters deeper into the material cross section of the base material.

The "thinner" component walls (0.5.. 3mm) are usually not prepared for welding seams, wherein welding with filler material (welding wire) is preferred, since there is a high risk of creating, for example, holes due to the absence of material (viewed in cross section). Especially in the case of gas metal welding (MSG), the filler material is often applied disadvantageously above the joint. Joining without the use of filler material, especially in the case of laser beam welding, results in a smaller joint cross section relative to the base material (depending on the joining technique and design), in which the forces result in higher stresses. Other defects in joints regulated and limited in DIN EN ISO 5817 further increase the stresses that occur locally, in particular due to the reduced cross-section of the joint that can withstand the loads and thus increase the probability of failure, for example inaccuracies such as edge height shifts and different gap widths in butt welding.

The combination or superposition of these causes of failure makes it necessary, in particular, to determine the thickness of the component in relation to the joint. Thus, while a greater component thickness is only required at the joint, the wall thickness of all components is oversized. High component thickness hinders overall lightweight construction and resource efficiency. The use of ultra-high-strength steels is thereby particularly limited, since in the case of said steels the metallurgical notch is particularly pronounced and the geometrical notch sensitivity is very high.

To reduce metallurgical notch peaks or to reduce stress peaks introduced by the joint, the joined components may be heat treated (annealed) to homogenize them. However, this heat treatment requires at least one further processing step and, due to the input of heat, can have an adverse effect on the particularly pronounced and intentionally set properties (microstructure, possibly a coating) of the component.

To reduce the sensitivity to geometrical notching, the joint can be machined, in particular by cutting, in order to reduce the possibility of cracks, in particular in the case of very high joints. This measure also requires at least one further process step and additional equipment expenditure.

US 1,161,419 describes a method for thermally connecting two sheets of sheet metal butted against each other. The thickness of the edges to be joined in the butt joint is increased by material displacement, thereby increasing the cross section of the seam. The enlargement of the weld as a geometric dimension makes it possible to increase the static load-bearing capacity of the connection between the metal sheets in the middle of the connection region.

With regard to the prior art, in particular in order to coordinate the strength distribution (metallurgical gap) and the geometry (geometric gap) in the joint/weld seam, further optimization is nevertheless required, in particular in the case of the processing of new thin-walled ultrahigh-strength steel materials, in particular depending to a large extent on the joining technique, the type of joint, the wall thickness and the materials used.

Disclosure of Invention

The object of the invention is to provide a method for thermally connecting two workpiece sections, with which a harmonious transition between the base material and the joint can be essentially achieved between the connected workpiece sections without additional processing steps.

This object is solved by a method for thermally connecting at least two workpiece sections having the features of claim 1. Further advantageous embodiments of the invention are set forth in the dependent claims.

According to the invention, a method for thermally connecting at least two workpiece sections is proposed, wherein at least a first and a second workpiece section are provided, wherein at least the first workpiece section comprises an edge and the edge defines a terminal end of the edge section, the first workpiece section and the second workpiece section being positioned relative to one another such that they are connected to one another at least in sections over their longitudinal extension, wherein the edge section has a defined geometry.

According to the invention, a first workpiece section is to be understood as an edge of a first workpiece having an associated edge section. According to the invention, a second workpiece section is to be understood as meaning the edge of the second workpiece with the associated edge section, or only the edge section of the second workpiece, or only the second workpiece as a section of the connecting section.

If the second workpiece section relates to an edge of the second workpiece having an associated edge section, the first workpiece section comprises the edge and the edge defines a terminal end of the edge section of the second workpiece, wherein the edge section has a defined geometry. The two edge sections of the two workpiece sections particularly preferably have the same geometry.

The defined geometry of the edge section is dimensioned in such a way that the arrangement in the cross section of the edge section has a maximum thickness t at a distance from the edge_maxOr in the lateral extension of the edge section, at least one strip having a maximum thickness t is arranged from the edge_maxIn particular a substantially constant maximum thickness t_maxOf (2) a section of (a).

The inventors have found that by designing the defined geometry and the corresponding dimensioning of the edge sections, a positive influence can be exerted on the manufacture of the harmonious transition regions between the base material and the joining seam extending between the joined workpiece sections, without substantial additional processing steps having to be taken into account in the manufacturing process for reducing the notch sensitivity. The defined or targeted manner and method of designing the geometry of the edge segments alleviates geometrical notches and ensures a uniform flow of force without stress peaks in the notch base. For example, the geometry of the edge sections is dimensioned in such a way that the connecting seams can substantially withstand the loads occurring or in the case of operating stresses due to the quotient of the operating force and the stress cross section, and in the case of a fault, the fault location is outside the connecting seam or the WEZ. The configuration according to the invention makes it possible to improve the static strength and/or the dynamic operating strength of the connection point.

On the one hand, the defined geometry of the edge section is dimensioned in such a way that a cross section of the edge section is provided with a maximum thickness t at a distance from the edge_maxThe local area of (a). Alternatively or in addition, in the transverse extension of the edge section, at least one strip having a maximum thickness t is provided starting from the edge_maxIn other words, a section of the edge section in the transverse extension is formed with a substantially constant thickness from the edge, which thickness corresponds to the maximum thickness t_maxWherein the section or its width is defined, in particular, according to the joining technique, the type of joint, the wall thickness and the material used, etc. In one aspect, the maximum thickness t_maxThe task of (a) is to compensate for the lower strength of the material in the joint seam (compensation for metallurgical gaps) and its position, both locally and in predetermined sections, is responsible for the homogenization and the direct-acting, non-deflecting flow of the forces between the two workpiece sections to be joined. Furthermore, the burn-through gaps, which are usually found, for example, at the edges of the connecting seams, are filled with the material deposited, so that the geometric gaps are homogenized and more material is present in the cross section than in the initial wall thickness (compensation of the geometric gaps).

Maximum thickness t_maxIn particular, it can be determined that: the standard joining device with at least two workpiece sections or at least two workpieces is examined and parameters are determined, for example the hardness distribution in the cross-section of the joining point region (base material of the first workpiece-WEZ of the first workpiece-joining seam between the first and second workpiece-WEZ of the second workpiece-second workpiece)The base material of the piece). In the heat affected zone WEZ, a decrease in the hardness distribution can generally be recognized. In order to be able to achieve an enhancement, in particular with regard to a reduction in the hardness or, in particular, a harmonic transition between the two workpieces, the thickness of at least the edge or edge section of the first workpiece is preferably set specifically to compensate for this reduction in hardness. The relative hardness reduction is based on the quotient of the hardness of the workpiece and the minimum hardness in the WEZ. This quotient is multiplied by the initial thickness or thickness t of the workpiece to be used and yields the desired maximum thickness t_maxIn order to be able to compensate for metallurgical gaps in particular. For example, the following formula may be used as the design maximum thickness t_maxThe formula of (a):

t_max＝t_workpiece(hardness)_WorkpieceHardness/hardness_{Minimum WEZ workpiece})，

Wherein t is_maxAnd t_WorkpieceIn mm, where the quotient of the two hardness values has no units, and the hardness values can be determined by all common hardness test methods (vickers, rockwell, brinell, etc.). The use of hardness as a parameter is basically based on simple determination and similar strength to steel.

A flat product with a substantially constant thickness t is preferably used as the workpiece. Prior to the thermal joining, at least the first workpiece section is subjected to a conventional forming, in particular a solid forming, with its edge and the edge section adjoining it, which results in a defined geometry of the edge section.

Thus, in the joined, welded state, a uniform local load is generated which has a cross-sectional stress distribution which is matched with respect to the local strength of the material after the thermal joining (welding) of the workpieces, and discontinuities in the cross-sectional distribution of the thermal joining can be substantially avoided (uniform, closed joining regions). Depending on the thickness of the workpiece or workpieces, the type of joint (joint type) and the material of the workpieces, there is little restriction on the design or size of the joint.

By the substantially uniformly formed connecting region, in addition to the static load-bearing capacity, the dynamic load-bearing capacity can be increased, so that the workpieces thermally connected according to the invention can be used in dynamic, periodic load regions. These are parts (component groups) of the chassis, especially in the manufacture of vehicles.

According to one embodiment, a workpiece is provided having a first and a second workpiece section, wherein the second workpiece section comprises an edge, and the edge defines a terminal end of the edge section, and the two edges are connected to one another at least in sections in their longitudinal extension, in order to produce an at least in sections closed profile. With the method according to the invention, it is possible to provide workpieces made of one-piece material (workpiece) in the form of profiles/parts which are closed at least in sections in the longitudinal extension, preferably profiles/components which are completely closed in the longitudinal direction, the metallurgical and geometrical notch sensitivity of which at the connecting seam is substantially minimized to a large extent. The correspondingly produced profile with a closed cross section is particularly preferably suitable for further processing into components by means of a production technology which is particularly supported by an effective medium, since faults in the connecting seam can be eliminated.

According to an alternative embodiment, a first workpiece having a first workpiece section and a second workpiece having a second workpiece section are provided, wherein the two workpiece sections are connected to one another at least in sections in the longitudinal extension in order to produce a workpiece group. With the method according to the invention, a workpiece set or a component set comprising at least two workpieces of the same or different materials and having the same or different thicknesses is connected to one another at least in sections, preferably completely, in the longitudinal extension, and a material set or a component set having a substantially largely minimized metallurgical and geometric notch sensitivity in the connecting seam is provided. The workpieces can be designed, for example, as two half-shells, for example with a U-shaped or C-shaped cross section, each having a base region with two projecting frame regions, so that the half-shells each have edge regions at the ends of the frames (regions), by means of which the half-shells can be connected to one another, in particular in a butt joint and/or overlap joint, to form a workpiece group/component group with a cross section that is at least partially, preferably completely, closed in the longitudinal direction. Other embodiments of the set of components/sets of components are also conceivable, for example, which differ from the closed cross section.

According to one embodiment, the edges are positioned at a distance from each other in the butt joint. This has the advantage that a predetermined gap can be provided, through which, depending on the joining technique and the wall thickness, a welding bath can be generated between the edges of the workpieces to be welded and in order not to weld over the joining seam. The distance or gap between the edges is at most the thickness t of the workpiece having the smaller thickness.

According to an alternative embodiment, the edges are positioned in contact with one another at least in sections in the butt joint. The at least sectionally contacting of the edges defines an at least sectionally technical zero gap, which can ensure a high-quality seam, in particular in the case of laser welding without filler material.

According to one embodiment, the edges are positioned in the butt joint with an edge height offset relative to each other. The edge height offset can be provided deliberately, for example, by using two workpieces of the same thickness or by using workpieces of different thicknesses, wherein the edge height offset is preferably provided on the side facing the side to be thermally loaded for the production of the connecting seam. This has the advantage that, especially in connection with seam tracking based on sensor technology, edge joints can be detected and preferably can be connected with a perfect zero gap by triangulation.

According to one embodiment, the edge sections are respectively positioned at an angle relative to each other.

According to an alternative embodiment, the second workpiece section defines an edge section of the second workpiece, and the edge sections are positioned relative to each other in the lap joint. The edge sections are oriented substantially parallel to each other. At least one edge, in particular two edges, or one associated edge section or two associated edge sections, has the geometry defined according to the invention.

According to a further alternative embodiment, the second workpiece section defines a section of the second workpiece as the connecting section, wherein the edge section of the first workpiece and the section of the second workpiece are positioned relative to each other in the T-joint. The edge sections are oriented substantially parallel to each other. Here, the edge of the first workpiece or the associated edge section has a geometry defined according to the invention.

According to one embodiment, the thermal connection is sensor controlled. The connection controlled by the sensor sets a suitable device with which the connection quality can be improved on the basis of a precise orientation/control of the heat source. The precise orientation improves repeatability accuracy and process reliability. Due to the high process reliability, the connection/joining speed can be increased, thereby improving economic efficiency.

According to one embodiment, the thermal connection is achieved by arc welding, beam welding, pressure welding, soldering or a hybrid method by a combination thereof.

According to one embodiment, the workpiece used is an uncoated steel material or alternatively a steel material provided with a coating that prevents corrosion, in particular with a metal coating, preferably with a zinc-based coating, and having a tensile strength Rm > 600 MPa. By means of the method according to the invention, particularly sensitive dual-phase, complex-phase or Q + P steel materials with tensile strengths Rm > 700MPa, in particular Rm > 800MPa, preferably Rm > 900MPa, preferably Rm > 1000MPa, can be joined particularly preferably thermally to a workpiece assembly/component assembly.

The thickness of the workpiece or workpieces is in particular constant and has a thickness of at most 4mm, preferably at most 3.5mm, preferably at most 3mm, particularly preferably at most 2.5mm, and a thickness of at least 0.3mm, in particular at least 0.5mm, preferably at least 0.7mm, particularly preferably at least 1 mm.

The workpiece is a workpiece made of a metal material, wherein a workpiece made of a steel material is preferably used. It is also conceivable to connect workpieces made of aluminum material with the same type or different types of material, for example also to connect steel material with aluminum material.

According to a further aspect of the invention, the workpiece assembly produced according to the invention is used as part of a chassis or part of a body of a vehicle, in particular an electric vehicle and/or a vehicle with an internal combustion engine. In a preferred use as part of a vehicle chassis, a durable and strong workpiece/component set can be provided which is designed to withstand cyclic loads in use and which can substantially preclude failure in the joint seam or WEZ.

Drawings

The invention is explained in more detail below with reference to the drawings. Like parts carry like reference numerals throughout.

In detail:

figure 1) shows a schematic partial cross-sectional view of a first embodiment of a set of workpieces,

figure 2) shows a schematic partial cross-sectional view of a second embodiment of a set of tools,

figure 3) shows a schematic partial cross-sectional view of a third embodiment of a workpiece group,

figure 4) shows a schematic partial cross-sectional view of a fourth embodiment of a workpiece group,

fig. 5) shows a schematic partial section of a fifth embodiment of a workpiece group, and

fig. 6) shows a schematic partial cross-sectional view of a sixth embodiment of a workpiece set.

Detailed Description

Fig. 1 shows a schematic partial section of a first embodiment of a workpiece set (10). The workpiece group (10) is produced according to the method according to the invention for thermally connecting at least two workpiece sections. A first workpiece (1) having a first workpiece section is provided, which comprises an edge (1.1) and the edge (1.1) defines a terminal end of the edge section (1.2), and a second workpiece (2) having a second workpiece section is provided, which comprises an edge (2.1) and the edge (2.1) defines a terminal end of the edge section (2.2), wherein, to produce the workpiece group (10), the two workpiece sections are connected to one another at least in sections in the longitudinal extension, preferably completely in the longitudinal extension, or by means of a connecting seam (3). The thermal connection can be achieved by arc welding, beam welding (laser welding), soldering or hybrid methods including combinations thereof, wherein the edges (1.1, 2.1) are positioned substantially at a distance from each other in the butt joint. In this embodiment, the connecting seam (3) is produced by laser hybrid welding. The workpieces (1, 2) can consist of the same or different materials with the same or different thicknessesWherein in this embodiment the thickness (t) of the workpieces (1, 2)_1,2) The same is true. At least one of the workpieces (1, 2), in particular both workpieces (1, 2), consists of an uncoated or coated steel material having a tensile strength Rm > 600 MPa. At least one of the workpieces (1, 2) is preferably composed of a dual-phase, complex-phase or Q + P steel material with a tensile strength Rm > 700 MPa.

At least one of the edge sections (1.2, 2.2), in particular both edge sections (1.2, 2.2), has a defined geometry which is dimensioned such that, in the transverse extension of the edge sections (1.2, 2.2), at least one edge section having a maximum thickness (t) is provided starting from the edge (1.1, 2.2)_max1,t_max2) In particular a substantially constant maximum thickness (t)_max1,t_max2) Section (1.3, 2.3). The section (1.3, 2.3) or the width thereof is dependent in particular on the WEZ (3.1), in particular on the region (5) of the metallurgical gap. The geometry of the edge section (1.2, 2.2) differs in particular from the geometry of the remaining region of the workpiece (1, 2), in particular the thickness (t)_1，2) And extends substantially in the transverse direction in the region (4) of the geometrical gap, and in particular in the region (5) of the metallurgical gap, or covers said region.

Fig. 2 shows a schematic partial cross-sectional view of a second exemplary embodiment of a workpiece set (10'). The workpiece group (10') is produced according to the method according to the invention for thermally connecting at least two workpiece sections. Providing a first workpiece (1') having a first workpiece section, which comprises an edge (1.1') and the edge (1.1') defines the end of the edge section (1.2'), and a second workpiece (2') having a second workpiece section, which comprises an edge (2.1') and the edge (2.1') defines the end of the edge section (2.2'), wherein, to produce the workpiece group (10'), the two workpiece sections are connected to one another at least in sections in the longitudinal extension, preferably completely in the longitudinal direction, or by means of a connecting seam (3'). The thermal connection can be achieved by means of arc welding, beam welding, soldering or a combination thereof, wherein the edges (1.1', 2.1') are positioned essentially in at least partial contact in the butt joint and the edge portions (1.2', 2.2') are angled relative to one anotherDegree (. alpha.) of_1'，2') And (6) positioning. In this embodiment, the connecting seam (3') is produced by MAG welding. Angle (alpha)_1'，2') < 180 °, in particular < 170 °, wherein for example no lower than an angle of 150 °. The workpieces (1', 2') can consist of the same or different materials with the same or different thicknesses, wherein in this embodiment the thickness (t) of the workpieces (1', 2') is_1'，2') The same is true. At least one of the workpieces (1', 2'), in particular both workpieces (1', 2'), consists of an uncoated or coated steel material having a tensile strength Rm > 600 MPa. At least one of the workpieces (1', 2') is preferably composed of a dual-phase, complex-phase or Q + P steel material with a tensile strength Rm > 700 MPa.

At least one of the edge sections (1.2', 2.2'), in particular both edge sections (1.2', 2.2'), has a defined geometry which is dimensioned such that in a cross section of the edge section (1.2', 2.2') a local region is provided which has a maximum thickness (t) at a distance (1.3', 2.3') from the edge (1.1', 2.1')_{max1'，max2'}). The geometry of the edge section (1.2', 2.2') differs from the geometry of the remaining region of the workpiece (1', 2'), in particular the thickness (t)_1'，2') In contrast, and in the transverse direction, substantially in the region (5) of the metallurgical gap or covers said region. The thickness of the workpiece (1', 2') is from the edge (1.1', 2.1') to have a maximum thickness (t)_{max1'，max2'}) Is increased (1.3', 2.3'). In particular, the increase in thickness occurs in the region (4') of the geometrical indentation. In the edge sections (1.2', 2.2'), the thickness is selected from the maximum thickness (t)_{max1'，max2'}) And away from the edge (1.1', 2.1'), is reduced again to the (initial) thickness (t) of the workpiece (1', 2')/of the local region (1.3', 2.3') of the workpiece (1', 2.1')_1'，2'). The thickness thereby varies along the cross section of the edge sections (1.2', 2.2').

Fig. 3 shows a schematic partial section of a third embodiment of a workpiece set (10'). The workpiece group (10') is produced according to the method according to the invention for thermally connecting at least two workpiece sections. Providing a first workpiece (1') having a first workpiece section comprising an edge (1.1') and the edge (1.1') defining a terminal end of the edge section (1.2')And a second workpiece (2') having a second workpiece section, which comprises an edge (2.1') and the edge (2.1') defines a terminal end of the edge section (2.2'), wherein, for producing the workpiece group (10'), the two workpiece sections are connected to one another at least in sections in the longitudinal direction, preferably completely in the longitudinal direction, or are connected to one another by a connecting seam (3'). According to the invention, only the edge section (1.2') of the first workpiece (1') is dimensioned such that, in the transverse extension of the edge section (1.2'), starting from the edge (1.1') a maximum thickness (t) is provided_max1") section (1.3"). The thickness (t) of the edge section (2.2') of the second workpiece (2')_2”) Substantially constant with the rest of the workpiece (2'). Furthermore, a geometrically notched region (4 ") and a metallurgically notched region (5") are shown, as well as a WEZ (3.1 ") region. The edges (1.1', 2.1') are positioned substantially in the butt joint, in particular at least in sections in contact, with an edge height offset (6) relative to each other. The edge height offset (6) is arranged on the side facing the side to which heat is applied for producing the connecting seam (3'). Thus, in combination with seam tracking based on sensor technology, edge joints can be detected and connected with an ideal zero gap by triangulation. The thermal coupling in this and other embodiments is performed in a sensor controlled manner, thereby improving coupling quality based on precise orientation/control of the heat source.

Fig. 4 shows a schematic partial cross-sectional view of a fourth embodiment of a set of workpieces (10 "'). The workpiece group (10') is produced according to the method according to the invention for thermally connecting at least two workpiece sections. A first workpiece (1') having a first workpiece section is provided, which comprises an edge (1.1') and the edge (1.1') defines a terminal end of the edge section (1.2'), and a second workpiece (2'), which has an edge (2.1') and a second workpiece section and the edge (2.1') defines the edge section (2.2'), wherein, for producing the workpiece group (10'), the two workpiece sections are connected to one another at least in sections in the longitudinal extension, preferably completely in the longitudinal extension, or by means of a seam (3'). The edge sections (1.2', 2.2') are joined together in an overlapping mannerPositioned in the head relative to each other. The edge sections (1.2', 2.2') are oriented substantially parallel to one another. Here, only the edge (1.1') or the associated edge section (1.2') of the first workpiece (1') has a modified geometry compared to the remaining region of the workpiece (1'), wherein a maximum thickness (t) is provided in the transverse extent of the edge section (1.2') starting from the edge (1.1')_max1") section (1.3"). This maximum thickness defines the maximum fillet thickness that can be achieved. The thickness (t) of the edge section (2.2') of the second workpiece (2')_2”) Is substantially constant with respect to the remaining area of the workpiece (2').

Fig. 5 shows a schematic partial cross-sectional view of a fifth embodiment of a set of components (10'). In contrast to the fourth exemplary embodiment, a second workpiece (2') is considered, which, like the first workpiece (1'), has a defined geometry of an edge (2.1') or an edge section (2.2'), wherein a defined geometry having a maximum thickness (t) is provided in the lateral extension of the edge section (2.2') starting from the edge (2.1')_max2”') Segment (2.3'). The section (1.3', 2.3') or the width thereof is determined in particular according to the WEZ (3.1 '), in particular according to the region (5') of the metallurgical gap, etc.

In addition to the arc welding used to produce the joints (3', 3') in the fourth and fifth exemplary embodiments, pressure welding, in particular resistance spot welding, may also be used instead.

Fig. 6 shows a schematic partial cross-sectional view of a sixth embodiment of a set of tools (10 ""). The workpiece group (10') is produced according to the method according to the invention for thermally connecting at least two workpiece sections. A first workpiece (1') is provided having a first workpiece section which comprises an edge (1.1') and the edge (1.1') defines the end of the edge section (1.2'), and a second workpiece (2') having a second workpiece section which defines a section (2.2') as a connecting region, wherein, for producing a workpiece group (10'), the two workpiece sections are connected to one another at least in sections in a longitudinal extension, preferably completely in a longitudinal extension, or by means of a seam (3'). An edge section (1.2') of the first workpiece (1') and a second workpiece (2') ") Are positioned relative to each other in a T-junction, wherein the direction of the edge section (1.2 "') is substantially perpendicular to the section (2.2" "). Only the edge (1.1') or the associated edge section (1.2') of the first workpiece (1') has a changed geometry compared to the rest of the workpiece (1'), wherein a maximum thickness (t) is provided starting from the edge (1.1') in the transverse extension of the edge section (1.2')_max1”') Segment (1.3 "'). The thickness (t) of a section (2.2') of the second workpiece (2') is_2””) Is substantially constant with respect to the remaining area of the workpiece (2'). The section (1.3') or the width thereof is determined in particular by the WEZ (3.1 '), in particular by the region (5') of the metallurgical gap, etc.

In principle, a profile/component made of a one-piece workpiece can also be produced, which is closed at least in sections in the longitudinal direction, wherein the workpiece sections of the workpiece to be connected can be designed, for example, analogously to one of the six exemplary embodiments shown.

The standard material group was produced from two workpieces made of HDT780C grade uncoated complex phase steel with a thickness t of 2mm each by means of MAG welds. The two workpieces also have a substantially constant thickness in the edge section up to the edge. The edges are positioned at a distance from each other that is less than the thickness of the workpiece, and the edge sections are positioned at an angle of about 160 ° to each other and are completely connected to each other in the longitudinal direction. Studies of the material groups showed that a geometrical notch area of about +/-2.5mm was formed on the left and right sides of the edge, and a metallurgical notch area of about +/-5mm was formed on the left and right sides of the edge, essentially reflecting and covering the WEZ. The hardness of the cross-section of the workpiece is substantially about 300HV 0.5, the Vickers hardness being determined according to DIN EN ISO 6507-2. In the outer region of the WEZ, which is remote from the region of the connecting seam, the hardness is approximately 250HV 0.5, which corresponds to a relative hardness reduction of 20%. Similarly to the second exemplary embodiment, two workpieces (1', 2') having defined edge sections (1.2', 2.2') are joined to one another to form a workpiece (10') in the same manner as the workpieces described above. In order to compensate for the zone (5') of metallurgical gap, the zone in which the minimum hardness of the WEZ of the set of workpieces is determined is locally reinforced. To compensate for the difference in hardness, the edgesA maximum thickness (t) of 2.4mm is set in the edge section (1.2', 2.2') at a distance (1.3', 2.3') of approximately 4mm from the edge (1.1', 2.1')/to_{max1'，max2'}) Where this corresponds to a relative increase of 20%. The edge sections (1.2', 2.2') have a transverse extent or a width of approximately 7.5 mm. The standard workpiece set and the workpiece set (10') are tested in a force-regulated cyclic vibration test

Shown in the figure. On the one hand, it can be demonstrated that the fault location of the standard workpiece set is in the WEZ region, whereas the fault of the workpiece set (10') occurs in the (base) material of one workpiece, not in the connecting region. Furthermore, this fracture behavior leads to a higher dynamic operating strength of the workpiece set (10').

The invention is not limited to the embodiments shown, but the individual features can be combined with one another in any desired manner. Different designs of the set of components/assemblies may also be presented. For example, it is also possible to connect only the edges of a one-piece workpiece to each other to produce a member/profile with a closed cross section. The material set (10, 10', 10 ", 10"', 10 "") is used as part of a chassis or part of a vehicle body. But may be used in other areas as well.

Claims

1. Method for thermally connecting at least two workpiece sections, wherein at least a first and a second workpiece section are provided, wherein at least the first workpiece section comprises an edge (1.1, 1.1'), and the edge (1.1, 1.1') defines a terminal end of the edge section (1.2, 1.2'), the first and the second workpiece section being positioned relative to each other in such a way that they are connected to each other at least sectionally over their longitudinal extension, wherein the edge section (1.2, 1.2') has a defined geometry,

it is characterized in that the preparation method is characterized in that,

the defined geometry of the edge section (1.2, 1.2') is dimensioned such that in the cross-section of the edge section (1.2') it is provided with a maximum distance (1.3') from the edge (1.1') in a cross-section of the edge section (1.2')Large thickness (t)_max1’) Or in the lateral extension of the edge section (1.2, 1.2'), at least one layer having a maximum thickness (t) is provided starting from the edge (1.1, 1.1') in the local region of (1.2, 1.2')_{max1，max1”，max1”’}) Segment (1.3, 1.3 ", 1.3"').

2. The method according to claim 1, wherein a workpiece is provided having a first and a second workpiece section, wherein the second workpiece section comprises an edge, and the edge defines a terminal end of the edge section, and the two edges are connected to each other at least in sections over their longitudinal extension, so as to produce an at least in sections closed profile.

3. The method according to claim 1, wherein a first workpiece (1, 1', 1 ", 1" ') having a first workpiece section and a second workpiece (2, 2', 2 ", 2" ', 2 "") having a second workpiece section are provided and the two workpiece sections are connected to one another at least in sections in longitudinal extension so as to produce a workpiece group (10, 10', 10 ", 10" ', 10 "", 10 "" ').

4. Method according to any of the preceding claims, wherein the edges (1.1, 2.1) are positioned at a distance from each other in the butt joint.

5. A method according to any one of claims 1 to 3, wherein the edges (1.1', 1.1 ", 2.1', 2.1") are positioned in contact with each other at least sectionally in the butt joint.

6. The method according to any of the preceding claims, wherein the edges (1.1 ", 2.1") are positioned relative to each other in the butt joint with an edge height offset (6).

7. Method according to any of the preceding claims, wherein the edge sections (1.2', 2.2') are each angled (α) relative to each other_1’，2’) And (6) positioning.

8. Method according to claim 1, wherein the second workpiece section defines an edge section (2.2 ", 2.2" ') of the second workpiece (2 ", 2" '), wherein the edge sections (1.2 ", 2.2", 2.2 "') are positioned relative to each other in a lap joint.

9. Method according to claim 1, wherein the second workpiece section defines one section (2.2 "") of the second workpiece (2 ""), wherein the edge section (1.2 "') of the first workpiece (1"') and said section (2.2 "") of the second workpiece (2 "") are positioned relative to each other in the T-joint.

10. The method according to any of the preceding claims, wherein the thermal connection is sensor controlled.

11. The method according to any of the preceding claims, wherein the thermal connection is achieved by arc welding, beam welding, pressure welding, soldering or a hybrid method by a combination thereof.

12. Method according to any one of the preceding claims, wherein the workpiece (1, 1', 1 ", 1"', 2, 2', 2 ", 2"', 2 "") used is uncoated or coated steel and the tensile strength Rm > 600 MPa.

13. The workpiece group (10, 10', 10 ", 10"', 10 "", 10 "" ') produced according to any one of claims 3 to 12, wherein the material group (10, 10', 10 ", 10" ', 10 "", 10 ""') is used as a part of a chassis or a part of a body of a vehicle.